Smart Actuator For Valve

ABSTRACT

A system and method of monitoring and controlling the open and close states of a manifold diaphragm type valve includes using an actuator mechanism with feedback control. A pressure transducer and/or force gauge located on the contact end of the actuator mechanism monitors the pressure and/or force applied to the end of the actuator mechanism. A controller instructs the actuator mechanism to move forward or backward an appropriate distance based on the monitored pressure and/or force. Temperature and pressure changes in the system and material changes to the diaphragm are sensed immediately and positioning correction is applied to the actuator in real-time, thereby maintaining the same valve state while monitoring pressure separately. The linear actuator functions as a ‘smart’ actuator, capable of fine tune adjustments without additional outside monitoring and providing a more accurate and reliable method of closing the valve in a dynamic environment.

CROSS-REFERENCE

The present application is a continuation application of U.S. patentapplication Ser. No. 14/077,112, entitled “Smart Actuator For Valve”,and filed on Nov. 11, 2013. The above-mentioned application is hereinincorporated by reference in its entirety.

FIELD

The present specification relates generally to valves used in fluidcircuits. More particularly, the present specification relates to anactuator mechanism for a valve having feedback control provided by apressure transducer and/or force gauge located on the contact end of theactuator.

BACKGROUND

Valves in fluid circuits typically have an open state and a closedstate, which is achieved by causing a linear actuator to extend towards,and press against, a membrane or diaphragm. In response, the diaphragmpushes into an orifice in the fluid pathway. The actuator continues topush the diaphragm into the orifice until the diaphragms contacts avalve seat opposite the actuator, thereby occluding fluid flow andclosing the valve. The reverse process, namely moving the actuator awayfrom the diaphragm and thereby releasing the diaphragm from compressionagainst the valve seat, opens the orifice and permits fluid to flow. Thelinear actuator is typically driven by a stepper motor and/or DC motoroperated by a controller. The system is preferably lightweight andconsumes minimum power, making it ideal for use in a variety ofapplications. The system can be used in conjunction with an orifice inany structure. In particular, an orifice is any hole, opening, void, orpartition in any type of material. This includes pathways in tubing,manifolds, disposable manifolds, channels, and other pathways.

Blood purification systems, which are used for conducting hemodialysis,hemodiafiltration or hemofiltration, involve the extracorporealcirculation of blood through an exchanger having a semi permeablemembrane. Such systems further include a hydraulic system forcirculating blood and a hydraulic system for circulating replacementfluid or dialysate comprising the certain blood electrolytes inconcentrations close to those of the blood of a healthy subject. Flow inthe fluid circuits is controlled by valves positioned in the fluid flowpathway. Examples of such fluid pathways include those disclosed in U.S.patent application Ser. No. 13/023,490, assigned to the applicant of thepresent invention, entitled “Portable Dialysis Machine” and filed onFeb. 8, 2011, which is incorporated herein by reference.

The valves are preferably implemented in a manifold using elasticmembranes at flow control points which are selectively occluded, asrequired, by protrusions, pins, or other members extending from themanifold machine. In some dialysis machines, fluid occlusion is enabledusing a safe, low-energy magnetic valve. Current valve systems often usea sensor, preferably an optical sensor, to determine the state of thevalve (open or closed).

While the optical sensor is useful for determining the open or closedstate of the valve and the position of the plunger, the prior art lacksa consistent and reliable mechanism for controlling the valve amidstchanges in the valve system. Current linear actuators do not include ameans for determining where or when to precisely stop pushing againstthe diaphragm (or membrane) in closing the valve, when to increasepressure to the diaphragm to keep the valve closed, or when to decreasepressure to a diaphragm that is being pulled via vacuum action in thefluid circuit. For example, over time, the diaphragm undergoesstructural changes due to exposure to sterilization methods, temperatureexposure, repeated strain, and pressure fluctuations within the system.Typically, the diaphragm material softens and thins. As these changesoccur, moving the actuator to the same position results in incompleteshut-off of fluid flow. The actuator must be advanced further into thediaphragm to achieve the same level of valve closure.

A liner actuator driven by a stepper motor and/or DC motor operated by acontroller can be used to deliver incremental changes to the actuatorposition. However, neither of these mechanisms allow for feedbackcontrol of actuator position through pressure or force sensing.Therefore, what is needed is an actuator mechanism for a manifoldmembrane/diaphragm type valve that allows for control of the positioningof the actuator based on feedback provided by a sensor located on thecontact end of the actuator.

SUMMARY

The present specification discloses a valve actuator system adapted toopen and close a valve, comprising an orifice closing member, positionedwithin a manifold and adjacent a fluid pathway through which fluid flowsin a dialysis system, said valve actuator mechanism comprising: adisplacement member adapted to being displaced linearly and having acontact end wherein said contact end is positioned proximate to saidorifice closing member when said valve is in said open state; a motorfor moving said displacement member; at least one pressure sensorpositioned on said contact end for sensing pressure generated when saidcontact end is in physical communication with said orifice closingmember and for relaying data based on said sensed pressure; and acontroller for receiving the sensed pressure from the at least onepressure sensor, wherein said controller comprises a memory havingstored therein a plurality of programmatic instructions that, whenexecuted by a processing unit, compare said sensed pressure to apre-determined value stored in said memory and activate said motor tomove said displacement member toward or away from said orifice closingmember to optimally position the contact end against said orificeclosing member.

The present specification also discloses a valve actuator system adaptedto open and close a valve, comprising an orifice closing member,positioned within a manifold and adjacent a fluid pathway through whichfluid flows in a dialysis system, said valve actuator mechanismcomprising: a displacement member adapted to being displaced linearlyand having a contact end wherein said contact end is positionedproximate to said orifice closing member when said valve is in said openstate; a motor for moving said displacement member; at least one forcesensor positioned on said contact end for sensing force generated whensaid contact end is in physical communication with said orifice closingmember and for relaying data based on said sensed force; and acontroller for receiving the sensed force from the at least one forcesensor, wherein said controller comprises a memory having stored thereina plurality of programmatic instructions that, when executed by aprocessing unit, compare said sensed force to a pre-determined valuestored in said memory and activate said motor to move said displacementmember toward or away from said orifice closing member to optimallyposition the contact end against said orifice closing member.

The present specification also discloses a valve actuator system adaptedto open and close a valve, comprising an orifice closing member,positioned within a manifold and adjacent a fluid pathway through whichfluid flows in a dialysis system, said valve actuator mechanismcomprising: a displacement member adapted to being displaced linearlyand having a contact end wherein said contact end is positionedproximate to said orifice closing member when said valve is in said openstate; a motor for moving said displacement member; at least onepressure sensor positioned on said contact end for sensing pressuregenerated when said contact end is in physical communication with saidorifice closing member and for relaying data based on said sensedpressure; at least one force gauge positioned on said contact end forsensing force generated when said contact end is in physicalcommunication with said orifice closing member and for relaying databased on said sensed force; and a controller for receiving the sensedpressure from the at least one pressure sensor and the sensed force fromthe at least one force gauge, wherein said controller comprises a memoryhaving stored therein a plurality of programmatic instructions that,when executed by a processing unit, compare said sensed pressure to apre-determined pressure value stored in said memory and said sensedforce to a pre-determined force value stored is said memory and activatesaid motor to move said displacement member toward or away from saidorifice closing member to optimally position the contact end againstsaid orifice closing member.

In various embodiments, the motor of any of the above valve actuatorsystems comprises a stepper motor. In other various embodiments, themotor of any of the above valve actuator systems comprises a DC motor.

In various embodiments, any of the above valve actuator systems furthercomprises an encoder for determining the amount of movement of saiddisplacement member.

In various embodiments, any of the above valve actuator systems is usedin a dialysis machine. In various embodiments, when used in a dialysismachine, the controller of the valve actuator system is programmed tomaintain a sensed pressure of at least 2 psi. In various embodiments,when used in a dialysis machine, the controller of the valve actuatorsystem is programmed to maintain a force of at least 5 pound-force(lb_(F)).

The present specification also discloses a method of controlling a valvestate of a fluid circuit, said method comprising the steps of: providinga valve component having an open position and a closed position andcomprising a controller and an orifice closing member adjacent to anorifice through which fluid can flow; providing an actuator mechanismcomprising: a displacement member having a contact end, wherein saidcontact end is adjacent to said orifice closing member when said valvecomponent is in said open position; a motor to exert a linear force onsaid displacement member to move said contact end of said displacementmember against said orifice closing member and cause said orificeclosing member to close said orifice; and, at least one sensorpositioned on said contact end for sensing a parameter applied to saidcontact end of said displacement member by said orifice closing member;activating said controller to instruct said actuator mechanism to movesaid displacement member toward and against said orifice closing membersuch that said displacement member pushes said orifice closing memberinto said orifice; sensing at least one parameter applied by saidorifice closing member against said contact end of said displacementmember using said sensor; relaying data regarding said sensed parameterfrom said sensor to said controller; comparing said data topre-determined values stored on said controller, wherein said controllercomprises a processing unit and a memory having stored therein aplurality of programmatic instructions and said pre-determined values;and, executing said programmatic instructions based on said comparisonto activate said actuator mechanism to move said displacement memberfurther toward or away from said orifice closing member such that saidorifice is substantially closed, thereby maintaining a closing force.

In one embodiment, said at least one sensor comprises a pressuretransducer and said at least one parameter comprises pressure. Inanother embodiment, said at least one sensor comprises a force gauge andsaid at least one parameter comprises force. In yet another embodiment,said at least one sensor comprises a pressure transducer and a forcegauge and said at least one parameter comprises pressure and force.

In one embodiment, the method further comprises the step of sensing saidat least one parameter while said contact end of said displacementmember is adjacent to said orifice closing member when said valve is insaid open position and prior to activating said controller to instructsaid actuator mechanism to move said displacement member toward andagainst said orifice closing member.

The aforementioned and other embodiments of the present invention shallbe described in greater depth in the drawings and detailed descriptionprovided below.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will befurther appreciated, as they become better understood by reference tothe detailed description when considered in connection with theaccompanying drawings:

FIG. 1A is an illustration of an actuator mechanism with feedbackcontrol, comprising a pressure transducer, and an open valve of a fluidcircuit, in accordance with one embodiment of the present specification;

FIG. 1B is an illustration of an actuator mechanism with feedbackcontrol, comprising a pressure transducer, and a closed valve of a fluidcircuit, in accordance with one embodiment of the present specification;

FIG. 2A is an illustration of an actuator mechanism with feedbackcontrol, comprising a force gauge, and an open valve of a fluid circuit,in accordance with one embodiment of the present specification;

FIG. 2B is an illustration of an actuator mechanism with feedbackcontrol, comprising a force gauge, and a closed valve of a fluidcircuit, in accordance with one embodiment of the present specification;

FIG. 3A is an illustration of an actuator mechanism with feedbackcontrol, comprising a pressure transducer and a force gauge, and an openvalve of a fluid circuit, in accordance with one embodiment of thepresent specification;

FIG. 3B is an illustration of an actuator mechanism with feedbackcontrol, comprising a pressure transducer and a force gauge, and aclosed valve of a fluid circuit, in accordance with one embodiment ofthe present specification;

FIG. 4A is a flow chart illustrating the steps involved in achieving avalve close state of a fluid circuit using an actuator mechanism withfeedback control, comprising a pressure transducer, as described withreference to FIGS. 1A and 1B;

FIG. 4B is a flow chart illustrating the steps involved in achieving avalve open state of a fluid circuit using an actuator mechanism withfeedback control, comprising a pressure transducer, as described withreference to FIGS. 1A and 1B;

FIG. 5A is a flow chart illustrating the steps involved in achieving avalve close state of a fluid circuit using an actuator mechanism withfeedback control, comprising a force gauge, as described with referenceto FIGS. 2A and 2B;

FIG. 5B is a flow chart illustrating the steps involved in achieving avalve open state of a fluid circuit using an actuator mechanism withfeedback control, comprising a force gauge, as described with referenceto FIGS. 2A and 2B;

FIG. 6A is a flow chart illustrating the steps involved in achieving avalve close state of a fluid circuit using an actuator mechanism withfeedback control, comprising a pressure transducer and a force gauge, asdescribed with reference to FIGS. 3A and 3B; and,

FIG. 6B is a flow chart illustrating the steps involved in achieving avalve open state of a fluid circuit using an actuator mechanism withfeedback control, comprising a pressure transducer and a force gauge, asdescribed with reference to FIGS. 3A and 3B.

DETAILED DESCRIPTION

The present specification discloses a system and a method of controllingactuator position for a diaphragm type valve of a fluid circuit based onfeedback provided by a pressure transducer and/or force gauge located onthe contact end of the actuator. In various embodiments, as a controlsignal and/or a voltage signal is applied to the linear actuator tocause the actuator to move to close the valve, a pressure transducer orforce gauge senses the feedback pressure or opposing applied force fromthe surface of the diaphragm. The sensed pressure or force is relayedvia firmware to a controller which then instructs the actuator to moveforward or backward an appropriate distance to maintain a constantpressure or force. As such, temperature and pressure changes in thesystem and material changes to the diaphragm are sensed immediately andpositioning correction is applied to the actuator in real-time, therebymaintaining the same valve state. In addition, changes due to thediaphragm as a result of exposure to sterilization methods can beaccounted for during operation. The linear actuator functions as a‘smart’ actuator, capable of fine tune adjustments without additionaloutside monitoring and provides a more accurate and reliable method ofclosing the valve. In various embodiments, the actuator accommodateschanges in force, pressure, temperature, flow, and/or viscosity of thefluid by continuously monitoring pressure and/or force at its contactend.

The actuator is programmed to advance and engage the membrane ordiaphragm of a valve of a fluid circuit. As the actuator is advanced, itpushes the diaphragm into the valve orifice until the diaphragm comesinto physical contact with a valve seat, thereby sealing the orifice andclosing the valve. The actuator includes a contact end that comes intophysical contact with the diaphragm and, in one embodiment, comprises apressure transducer on the contact end.

Upon initial engagement of the diaphragm via the pressure transducer, avoltage signal input (feedback) to the controller is produced. Thisfeedback, a positive voltage type or voltage increase, communicates tothe controller that the actuator has located the diaphragm. Thecontroller then controls the actuator, via firmware, to reversedirection until the point of 0 volts (no contact) feedback to thecontroller. This puts the pressure sensor in an optimum sensing positionbecause the actuator was extended until contact (positive voltage) wasachieved and then incrementally retracted such that no positive voltageoffset is being sent to the controller. Accordingly, the controllerfirmware does not have to negate this offset voltage.

When the controller is engaging the actuator to close the valve portthat the diaphragm is covering, the actuator linearly pushes up againstthe diaphragm until the diaphragm engages the port/valve orifice, thusclosing off any fluid flow. During the engagement of closing the valve,the positive voltage increases from the pressure transducer to a knownclosure value (an experimentally derived predetermined value) to closeoff the valve. If, during the course of operation, the diaphragm beginsto thin or soften due to temperature changes or other effects, thepressure transducer will sense a decrease in pressure at the contact endof the actuator. This decrease in pressure will translate to a decreasein positive voltage which will be relayed to the controller. Thecontroller will then instruct the actuator to extend further until thevoltage value once again matches the known closure value, signifyingthat the weakened diaphragm has been pushed further onto the valve seatto ensure complete valve closure. When the controller engages theactuator to open the valve port that the diaphragm is covering, theactuator moves linearly in the opposite direction (backwards away fromthe diaphragm) until the diaphragm releases from the port/valve orifice,thus allowing the flow of fluid through the space between the diaphragmand the valve port. As the diaphragm moves away from the valve port, thesensed pressure will decrease, signifying that the valve has beenreturned to an open state.

In various embodiments, the controller can be executed entirely inhardware or in software stored in a memory that may be local to, orremote from, the valve actuator mechanism. The controller steps areachieved by a processor executing the software stored in said memorywherein said memory includes a plurality of programmatic instructions.The processor receives data from the pressure transducer and, based upona comparison of said data to pre-determined pressure values, executesthe software stored in the memory to maintain the valve in a closedstate. The processor is also capable of receiving commands from a uservia a user interface to open or close the valve. In one embodiment, thecontroller is a software-based controller that is executed by a generalprocessor located entirely within a controller unit of a dialysismachine.

In another embodiment, the actuator comprises a force gauge on thecontact face. Upon initial engagement of the diaphragm via the forcegauge, a voltage signal input (feedback) to the controller is produced.This feedback, a positive voltage type or voltage increase, tells thecontroller that the actuator has located the diaphragm. The controllerthen controls the actuator, via firmware, to reverse direction until thepoint of 0 volts (no contact) feedback to the controller. This puts theforce gauge in an optimum sensing position without having a positivevoltage offset being sent to the controller. The controller firmwaredoes not have to negate this offset voltage.

When the controller is engaging the actuator to close the valve portthat the diaphragm is covering, the actuator linearly pushes up againstthe diaphragm until the diaphragm engages the port/valve orifice, thusclosing off any fluid flow. During the engagement of closing the valve,the positive voltage increases from the force gauge to a known closurevalue (an experimentally derived predetermined value) to close off thevalve. If, during the course of operation, the diaphragm begins to thinor soften due to temperature changes or other effects, the force gaugewill sense a decrease in force at the contact end of the actuator. Thisdecrease in force will translate to a decrease in positive voltage whichwill be relayed to the controller. The controller will then instruct theactuator to extend further until the voltage value once again matchesthe known closure value, signifying that the weakened diaphragm has beenpushed further onto the valve seat to ensure complete valve closure.When the controller engages the actuator to open the valve port that thediaphragm is covering, the actuator moves linearly in the oppositedirection (backwards away from the diaphragm) until the diaphragmreleases from the port/valve orifice, thus allowing the flow of fluidthrough the space between the diaphragm and the valve port. As thediaphragm moves away from the valve port, the sensed force willdecrease, signifying that the valve has been returned to an open state.

In various embodiments, the controller can be executed entirely inhardware or in software stored in a memory that may be local to, orremote from, the valve actuator mechanism. The controller steps areachieved by a processor executing the software stored in said memorywherein said memory includes a plurality of programmatic instructions.The processor receives data from the force gauge and, based upon acomparison of said data to pre-determined force values, executes thesoftware stored in the memory to maintain the valve in a closed state.The processor is also capable of receiving commands from a user via auser interface to open or close the valve. In one embodiment, thecontroller is a software-based controller that is executed by a generalprocessor located entirely within a controller unit of a dialysismachine.

In yet another embodiment, the actuator comprises both a pressuretransducer and a force gauge on the contact face. Upon initialengagement of the diaphragm via the pressure transducer and force gauge,the pressure transducer and the force gauge both send a voltage signalinput (feedback) to the controller. This feedback, a positive voltagetype or voltage increase, tells the controller that the actuator haslocated the diaphragm. At this point, the controller then controls theactuator, via firmware, to reverse direction until the point of 0 volts(no contact) feedback to the controller. The controller firmware doesnot have to negate this offset voltage. This puts the pressure sensorand force gauge in an optimum sensing position without having a positivevoltage offset being sent to the controller.

When the controller is engaging the actuator to close the valve portthat the diaphragm is covering, the actuator linearly pushes up againstthe diaphragm until the diaphragm engages the port/valve orifice, thusclosing off any fluid flow. During the engagement of closing the valve,the positive voltage increases from the pressure transducer and theforce gauge to a known closure value (an experimentally derivedpredetermined value) to close off the valve. If, during the course ofoperation, the diaphragm begins to thin or soften due to temperaturechanges or other effects, the pressure transducer will sense a decreasein pressure and the force gauge will sense a decrease in force at thecontact end of the actuator. This decrease in pressure and force willtranslate to decreases in positive voltage which will be relayed to thecontroller. The controller will then instruct the actuator to extendfurther until the voltage values once again match the known closurevalues, signifying that the weakened diaphragm has been pushed furtheronto the valve seat to ensure complete valve closure. When thecontroller engages the actuator to open the valve port that thediaphragm is covering, the actuator moves linearly in the oppositedirection (backwards away from the diaphragm) until the diaphragmreleases from the port/valve orifice, thus allowing the flow of fluidthrough the space between the diaphragm and the valve port. As thediaphragm moves away from the valve port, the sensed pressure and forcewill decrease, signifying that the valve has been returned to an openstate.

In various embodiments, the controller can be executed entirely inhardware or in software stored in a memory that may be local to, orremote from, the valve actuator mechanism. The controller steps areachieved by a processor executing the software stored in said memorywherein said memory includes a plurality of programmatic instructions.The processor receives data from the pressure transducer and force gaugeand, based upon a comparison of said data to pre-determined pressure andforce values, executes the software stored in the memory to maintain thevalve in a closed state. The processor is also capable of receivingcommands from a user via a user interface to open or close the valve. Inone embodiment, the controller is a software-based controller that isexecuted by a general processor located entirely within a controllerunit of a dialysis machine.

Upon full closure of the valve, the pressure transducer can monitorfluid pressure that is engaging the face of the pressure transducerwhile the force gauge monitors the force needed to keep the valve closeddue to possible changes in temperature, fluid density changes, and/ormedia density changes, thus maintaining a constant pressure as sensed bythe force gauge. In this position or operational mode, the pressuretransducer can monitor the negative or positive pressure of the orificeindependently.

In various embodiments, the pressure and/or force sensing can becontinuous or performed at specific time intervals and/or incrementalstages. For example, pressure and/or force can be sensed every 1milliseconds, 1 second, 30 seconds, 1 minute, 5 minutes, 30 minutes, 1hour, or any other time interval. In addition, in various embodiments,pressure and/or force can be sensing can be performed at specific timeintervals until the sensed pressure and/or force value crosses apre-determined threshold after which said sensing switches tocontinuous. For example, when diaphragm weakening is suspected based oninterval pressure or force sensing, the system can switch to continuoussensing to monitor a possibly failing diaphragm to ensure proper valvefunctioning.

In various embodiments, optimum pressure and/or force levels to ensureproper valve function can be determined based upon a normalization of afinal pressure and/or force state relative to any of the earlier sensedpressure and/or force values.

The present specification discloses multiple embodiments. The followingdisclosure is provided in order to enable a person having ordinary skillin the art to practice the invention. Language used in thisspecification should not be interpreted as a general disavowal of anyone specific embodiment or used to limit the claims beyond the meaningof the terms used therein. The general principles defined herein may beapplied to other embodiments and applications without departing from thespirit and scope of the invention. Also, the terminology and phraseologyused is for the purpose of describing exemplary embodiments and shouldnot be considered limiting. Thus, the present invention is to beaccorded the widest scope encompassing numerous alternatives,modifications and equivalents consistent with the principles andfeatures disclosed. For purpose of clarity, details relating totechnical material that is known in the technical fields related to theinvention have not been described in detail so as not to unnecessarilyobscure the present invention.

In various embodiments, the actuator mechanism with feedback controlsystem of the present specification comprises a linear actuator drivenby a stepper motor and/or DC motor operated by a controller, wherein thefeedback is provided by a pressure transducer and/or force gauge locatedon the contact end of the actuator. The system is lightweight andconsumes minimum power, making it ideal for use in a variety ofapplications. The system can be used in conjunction with an orifice inany structure. In particular, an orifice is any hole, opening, void, orpartition in any type of material. This includes pathways in tubing,manifolds, disposable manifolds, channels, and other pathways.

FIGS. 1A and 1B are illustrations of an actuator mechanism 110 withfeedback control, comprising a pressure transducer 114, and an openvalve and a closed valve, respectively, of a fluid circuit, inaccordance with one embodiment of the present specification. Referringto both FIGS. 1A and 1B simultaneously, each actuator mechanism 110includes an encoder 111, a stepper or DC linear actuator motor 112, anactuator plunger 113, an actuator mechanism body 128, a pressuretransducer 114, and a pressure transducer holder 115. A signal wire 117connects the pressure transducer 114 to a controller (not shown). Apower and signal wire 119 connects the motor 112 to the controller. Theencoder 111 acts to notify the system that the actuator mechanism ismoving.

Referring to FIG. 1A, the actuator (pressure transducer 114 in thisembodiment) is in its ‘home’ position within the front plate 130 of amachine system. The pressure transducer 114 functions as a linear membercontained within a conduit (in this embodiment, a front plate 130 of amachine system) through which it extends axially. Specifically, when theactuator is in its ‘home’ position, the pressure transducer 114 of theactuator mechanism 110 rests embedded within the front plate 130 of amachine system, such as, in one embodiment, a portion of a dialysissystem housing. In one embodiment, when the actuator is in the ‘home’position, the pressure transducer 114 rests within the front plate 130such that the contact end 114′ of the pressure transducer 114 ispositioned just proximal to, with respect to the actuator mechanism 110,an outer surface 130′ of the front plate 130. In other words, when theactuator is in the ‘home’ position, the contact end 114′ of the pressuretransducer 114 is slightly recessed within the front plate 130. Thepressure transducer 114 is linearly movable within the front plate 130by activation of the motor 112 and linear movement of the actuatorplunger 113 and pressure transducer holder 115. The pressure transducer114 can be moved forward, with respect to the actuator mechanism 110,such that its contact end 114′ extends beyond the outer surface 130′ ofthe front plate 130. A fluid pathway 150 is positioned proximate, oradjacent to, the front plate 130. A diaphragm 118 is positioned in anouter wall 150′ of the fluid pathway 150. In one embodiment, the outerwall 150′ of the fluid pathway 150 is positioned proximate and adjacentto the outer surface 130′ of the front plate 130 such that the diaphragm118 is proximate to, and in linear alignment with, the pressuretransducer 114 of the actuator mechanism 110. Since the actuatormechanism 110 is in the ‘home’ state, the diaphragm 118 is flat and isnot in contact with the pressure transducer 114, and the valve is in theopen state. Within the fluid pathway 150, a gap 158 at the valve 161 ispresent between the diaphragm 118 and valve seat 155, allowing fluid toflow through.

In one embodiment, referring to FIG. 1A, the components of the actuatormechanism 110 are arranged in the following configuration. As mentionedabove, in one embodiment, the pressure transducer 114 functions as theactuator. The pressure transducer 114, pressure transducer holder 115,and actuator plunger 113 are linearly movable as a unit via operation ofthe motor 112 and extend axially throughout the actuator mechanism 110.Using the diaphragm 118 of the outer wall 150′ of the fluid pathway 150as a reference point, the encoder 111 comprises the distal endpoint ofthe actuator mechanism 110. In one embodiment, a portion of the actuatorplunger 113 extends distally from the distal end of the encoder 111.During operation, as the motor 112 moves the actuator plunger 113 towardthe diaphragm 118, the portion of the plunger 113 extending from thedistal end of the encoder 111 moves proximally through said encoder 111.

Next to the encoder 111 and at a position more proximal to the diaphragm118 is the motor 112. The plunger 113 extends axially through the motor112. Positioned proximal to the motor 112 is the actuator mechanism body128. The distal end of the actuator mechanism body 128 is positionedadjacent to motor 112 and the proximal end of the actuator mechanism 128is positioned adjacent to the front plate 130 of the machine system. Aproximal portion of the actuator plunger 113 extends through the distalportion of the actuator mechanism body 128. Attached to the proximal endof the actuator plunger 113 and housed within the actuator mechanismbody 128 is the pressure transducer holder 115. Through action of themotor 112 and extension/retraction of the actuator plunger 113, thepressure transducer holder 115 is linearly movable within the actuatormechanism body 128. Attached to a proximal end of the pressuretransducer holder 115 is the pressure transducer 114. The pressuretransducer 114 extends axially partially through the actuator mechanismbody 128 and partially through the front plate 130. The pressuretransducer 114 is linearly movable within the proximal portion of theactuator mechanism body 128 and the front plate 130 via operation of themotor 112 and movement of the actuator plunger 113 and pressuretransducer holder 115.

Referring to FIG. 1B, the actuator mechanism 110 is in an ‘extended’position with the pressure transducer 114 moved forward through thefront plate 130 of the machine system such that the contact end 114′ ofthe pressure transducer 114 extends distally, with respect to theactuator mechanism 110, beyond the outer surface 130′ of the front plate130. The diaphragm 118 has been pushed into the fluid pathway 150through physical contact with the contact end 114′ of the pressuretransducer 114. In accordance with various embodiments of the presentspecification, based on feedback provided to the controller by thepressure transducer 114, the controller has instructed the motor 112 tomove the actuator plunger 113 to extend the pressure transducer holder115 and pressure transducer 114 such that the contact end 114′ of thepressure transducer 114 has come into contact with, and pushed forward,the diaphragm 118. The diaphragm 118 is extended into the fluid pathway150 and is in contact with the valve seat 155, effectively closing thevalve 161 and shutting off fluid flow. The gap at valve seat 155, asseen as gap 158 in FIG. 1A, has been closed in FIG. 1B. Pressure 170increases around the diaphragm 118 and valve seat 155 and pushes againstthe diaphragm 118.

FIGS. 2A and 2B are illustrations of an actuator mechanism 210 withfeedback control, comprising a force gauge 220, and an open valve and aclosed valve, respectively, of a fluid circuit, in accordance with oneembodiment of the present specification. Referring to both FIGS. 2A and2B simultaneously, each actuator mechanism 210 includes an encoder 211,a stepper or DC linear actuator motor 212, an actuator plunger 213, anactuator mechanism body 228, a force gauge 220, and a force gauge holder225. A signal wire 216 connects the force gauge 220 to a controller (notshown). A power and signal wire 219 connects the motor 212 to thecontroller. The encoder 211 acts to notify the system that the actuatormechanism is moving.

Referring to FIG. 2A, the actuator (force gauge 220 in this embodiment)is in its ‘home’ position within the front plate 230 of a machinesystem. The force gauge 220 functions as a linear member containedwithin a conduit (in this embodiment, a front plate 230 of a machinesystem) through which it extends axially. Specifically, when theactuator is in its ‘home’ position, the force gauge 220 of the actuatormechanism 210 rests embedded within the front plate 230 of a machinesystem, such as, in one embodiment, a portion of a dialysis systemhousing. In one embodiment, when the actuator is in the ‘home’ position,the force gauge 220 rests within the front plate 230 such that thecontact end 220′ of the force gauge 220 is positioned just proximal to,with respect to the actuator mechanism 210, an outer surface 230′ of thefront plate 230. In other words, when the actuator is in the ‘home’position, the contact end 220′ of the force gauge 220 is slightlyrecessed within the front plate 230. The force gauge 220 is linearlymovable within the front plate 230 by activation of the motor 212 andlinear movement of the actuator plunger 213 and force gauge holder 225.The force gauge 220 can be moved forward, with respect to the actuatormechanism 210, such that its contact end 220′ extends beyond the outersurface 230′ of the front plate 230. A fluid pathway 250 is positionedproximate, or adjacent to, the front plate 230. A diaphragm 218 ispositioned in an outer wall 250′ of the fluid pathway 250. In oneembodiment, the outer wall 250′ of the fluid pathway 250 is positionedproximate and adjacent to the outer surface 230′ of the front plate 230such that the diaphragm 218 is proximate to, and in linear alignmentwith, the force gauge 220 of the actuator mechanism 210. Since theactuator mechanism 210 is in the ‘home’ state, the diaphragm 218 is flatand is not in contact with the force gauge 220, and the valve is in theopen state. Within the fluid pathway 250, a gap 258 at the valve 261 ispresent between the diaphragm 218 and valve seat 255, allowing fluid toflow through.

In one embodiment, referring to FIG. 2A, the components of the actuatormechanism 210 are arranged in the following configuration. As mentionedabove, in one embodiment, the force gauge 220 functions as the actuator.The force gauge 220, force gauge holder 225, and actuator plunger 213are linearly movable as a unit via operation of the motor 212 and extendaxially throughout the actuator mechanism 210. Using the diaphragm 218of the outer wall 250′ of the fluid pathway 250 as a reference point,the encoder 211 comprises the distal endpoint of the actuator mechanism210. In one embodiment, a portion of the actuator plunger 213 extendsdistally from the distal end of the encoder 211. During operation, asthe motor 212 moves the actuator plunger 213 toward the diaphragm 218,the portion of the plunger 213 extending from the distal end of theencoder 211 moves proximally through said encoder 211. Next to theencoder 211 and at a position more proximal to the diaphragm 218 is themotor 212. The plunger 213 extends axially through the motor 212.Positioned proximal to the motor 212 is the actuator mechanism body 228.The distal end of the actuator mechanism body 228 is positioned adjacentto motor 212 and the proximal end of the actuator mechanism 228 ispositioned adjacent to the front plate 230 of the machine system. Aproximal portion of the actuator plunger 213 extends through the distalportion of the actuator mechanism body 228. Attached to the proximal endof the actuator plunger 213 and housed within the actuator mechanismbody 228 is the force gauge holder 225. Through action of the motor 212and extension/retraction of the actuator plunger 213, the force gaugeholder 225 is linearly movable within the actuator mechanism body 228.Attached to a proximal end of the force gauge holder 225 is the forcegauge 220. The force gauge 220 extends axially partially through theactuator mechanism body 228 and partially through the front plate 230.The force gauge 220 is linearly movable within the proximal portion ofthe actuator mechanism body 228 and the front plate 230 via operation ofthe motor 212 and movement of the actuator plunger 213 and force gaugeholder 225.

Referring to FIG. 2B, the actuator mechanism 210 is in an ‘extended’position with the force gauge 220 moved forward through the front plate230 of the machine system such that the contact end 220′ of the forcegauge 220 extends distally, with respect to the actuator mechanism 210,beyond the outer surface 230′ of the front plate 230. The diaphragm 218has been pushed into the fluid pathway 250 through physical contact withthe contact end 220′ of the force gauge 220. In accordance with variousembodiments of the present specification, based on feedback provided tothe controller by the force gauge, the controller has instructed themotor 212 to move the actuator plunger 213 to extend the force gaugeholder 225 and force gauge 220 such that the contact end 220′ of theforce gauge 220 has come into contact with, and pushed forward, thediaphragm 218. The diaphragm 218 is extended into the fluid pathway 250and is in contact with the valve seat 255, effectively closing the valve261 and shutting off fluid flow. The gap at valve seat 255, as seen asgap 258 in FIG. 2A, has been closed in FIG. 2B. Pressure 270 increasesaround the diaphragm 218 and valve seat 255 and pushes against thediaphragm 218.

FIGS. 3A and 3B are illustrations of an actuator mechanism 310 withfeedback control, comprising both a pressure transducer 314 and a forcegauge 320, and an open valve and a closed valve, respectively, of afluid circuit, in accordance with one embodiment of the presentspecification. Referring to both FIGS. 3A and 3B simultaneously, eachactuator mechanism 310 includes an encoder 311, a stepper or DC linearactuator motor 312, an actuator plunger 313, an actuator mechanism body328, a pressure transducer 314, a force gauge 320, and a pressuretransducer/force gauge holder 325. A first signal wire 317 connects thepressure transducer 314 to a controller (not shown). A second signalwire 316 connects the force gauge 320 to a controller. A power andsignal wire 319 connects the motor 312 to the controller. The encoder311 acts to notify the system that the actuator mechanism is moving.

Referring to FIG. 3A, the actuator (pressure transducer 314 and forcegauge 320 in this embodiment) is in its ‘home’ position within the frontplate 330 of a machine system. The pressure transducer 314 and forcegauge 320 function together as a linear member contained within aconduit (in this embodiment, a front plate 330 of a machine system)through which they extend axially. In one embodiment, the pressuretransducer 314 and force gauge 320 are configured to sit adjacent oneanother within the front plate 330. In another embodiment, the pressuretransducer 314 and force gauge 320 are configured to sit coaxially, onewithin the other, within the front plate 330. Specifically, when theactuator is in its ‘home’ position, the pressure transducer 314 andforce gauge 320 of the actuator mechanism 310 rest embedded within thefront plate 330 of a machine system, such as, in one embodiment, aportion of a dialysis system housing. In one embodiment, when theactuator is in the ‘home’ position, the pressure transducer 314 andforce gauge 320 rest within the front plate 330 such that the contactend 314′ of the pressure transducer 314 and the contact end 320′ of theforce gauge 320 are positioned just proximal to, with respect to theactuator mechanism 310, an outer surface 330′ of the front plate 330. Inother words, when the actuator is in the ‘home’ position, the contactend 314′ of the pressure transducer 314 and the contact end 320′ of theforce gauge 320 are slightly recessed within the front plate 130. Thecontact ends 314′, 320′ are flush with one another. The pressuretransducer 314 and force gauge 320 are linearly movable within the frontplate 330 by activation of the motor 312 and linear movement of theactuator plunger 313 and pressure transducer/force gauge holder 325. Thepressure transducer 314 and force gauge 320 can be moved forward, withrespect to the actuator mechanism 310, such that their contact ends314′, 320′ extend in unison beyond the outer surface 330′ of the frontplate 330. A fluid pathway 350 is positioned proximate, or adjacent to,the front plate 330. A diaphragm 318 is positioned in an outer wall 350′of the fluid pathway 350. In one embodiment, the outer wall 350′ of thefluid pathway 350 is positioned proximate and adjacent to the outersurface 330′ of the front plate 330 such that the diaphragm 318 isproximate to, and in linear alignment with, the pressure transducer 314and force gauge 320 of the actuator mechanism 310. Since the actuatormechanism 310 is in the ‘home’ state, the diaphragm 318 is flat and isnot in contact with either the pressure transducer 314 or the forcegauge 320, and the valve is in the open state. Within the fluid pathway350, a gap 358 at the valve 361 is present between the diaphragm 318 andvalve seat 355, allowing fluid to flow through.

In one embodiment, referring to FIG. 3A, the components of the actuatormechanism 310 are arranged in the following configuration. As mentionedabove, in one embodiment, the pressure transducer 314 and force gauge320 function together as the actuator. The pressure transducer 314 andforce gauge 320, pressure transducer/force gauge holder 325, andactuator plunger 313 are linearly movable as a unit via operation of themotor 312 and extend axially throughout the actuator mechanism 310.Using the diaphragm 318 of the outer wall 350′ of the fluid pathway 350as a reference point, the encoder 311 comprises the distal endpoint ofthe actuator mechanism 310. In one embodiment, a portion of the actuatorplunger 313 extends distally from the distal end of the encoder 311.During operation, as the motor 312 moves the actuator plunger 313 towardthe diaphragm 318, the portion of the plunger 313 extending from thedistal end of the encoder 311 moves proximally through said encoder 311.

Next to the encoder 311 and at a position more proximal to the diaphragm318 is the motor 312. The plunger 313 extends axially through the motor312. Positioned proximal to the motor 312 is the actuator mechanism body328. The distal end of the actuator mechanism body 328 is positionedadjacent to motor 312 and the proximal end of the actuator mechanism 328is positioned adjacent to the front plate 330 of the machine system. Aproximal portion of the actuator plunger 313 extends through the distalportion of the actuator mechanism body 328. Attached to the proximal endof the actuator plunger 313 and housed within the actuator mechanismbody 328 is the pressure transducer/force gauge holder 325. Throughaction of the motor 312 and extension/retraction of the actuator plunger313, the pressure transducer/force gauge holder 325 is linearly movablewithin the actuator mechanism body 328. Attached to a proximal end ofthe pressure transducer/force gauge holder 325 are the pressuretransducer 314 and force gauge 320. The pressure transducer 314 andforce gauge 320 extend axially partially through the actuator mechanismbody 328 and partially through the front plate 330. The pressuretransducer 314 and force gauge 320 are linearly movable within theproximal portion of the actuator mechanism body 328 and the front plate330 via operation of the motor 312 and movement of the actuator plunger313 and pressure transducer/force gauge holder 325.

Referring to FIG. 3B, the actuator mechanism 310 is in an ‘extended’position with the pressure transducer 314 and force gauge 320 movedforward through the front plate 330 of the machine system such that thecontact end 314′ of the pressure transducer 114 and the contact end ofthe force gauge 320′ extend distally, with respect to the actuatormechanism 310, beyond the outer surface 330′ of the front plate 330. Thediaphragm 318 has been pushed into the fluid pathway 350 throughphysical contact with both the contact end 314′ of the pressuretransducer 314 and the contact end 320′ of the force gauge 320. Inaccordance with various embodiments of the present specification, basedon feedback provided to the controller by the pressure transducer 314and force gauge 320, the controller has instructed the motor 312 to movethe actuator plunger 313 to extend the pressure transducer/force gaugeholder 325, pressure transducer 314, and force gauge 320, such that boththe contact end 314′ of the pressure transducer 314 and the contact end320′ of the force gauge 320 have come into contact with, and pushedforward, the diaphragm 318. The diaphragm 318 is extended into the fluidpathway 350 and is in contact with the valve seat 355, effectivelyclosing the valve 361 and shutting off fluid flow. The gap at valve seat355, as seen as gap 358 in FIG. 3A, has been closed in FIG. 3B. Pressure370 increases around the diaphragm 318 and valve seat 355 and pushesagainst the diaphragm 318.

In the above embodiments, as the diaphragm begins to thin or soften dueto temperature changes or other effects, the pressure transducer willsense a decrease in pressure and/or the force gauge will sense adecrease in force at the contact end of the actuator. This decrease inpressure and/or force will translate to a decrease in positive voltagewhich will be relayed to the controller. The controller will theninstruct the actuator to extend further until the voltage values onceagain match the known closure values, signifying that the weakeneddiaphragm has been pushed further onto the valve seat to ensure completevalve closure.

FIG. 4A is a flow chart illustrating the steps involved in achieving avalve close state of a fluid circuit using an actuator mechanism withfeedback control, comprising a pressure transducer, as described withreference to FIGS. 1A and 1B. At step 422, the controller instructs theactuator mechanism to extend the actuator plunger such that the pressuretransducer on the contact end of the actuator mechanism engages thediaphragm. Optionally, at step 424, the pressure transducer sensespressure applied by the diaphragm against the pressure transducer. Then,at step 426, the controller instructs the actuator mechanism to closethe valve by further extending the contact end of the actuator mechanismto push the diaphragm into the flow path of the fluid circuit. Thepressure transducer then senses the pressure applied against thetransducer by the diaphragm while the valve is in a closed state at step428. The sensed pressure is relayed to the controller at step 430. Atstep 432, the controller compares the sensed pressure value to apre-determined pressure value. The controller then instructs theactuator mechanism to further extend or retract the actuator plunger atstep 434 such that the sensed pressure matches the pre-determinedpressure value, thereby ensuring complete valve closure. The pressure iscontinually sensed at step 428 so that fine tune adjustments to theactuator position can be made in real-time to maintain the valve in aclose state.

FIG. 4B is a flow chart illustrating the steps involved in achieving avalve open state of a fluid circuit using an actuator mechanism withfeedback control, comprising a pressure transducer, as described withreference to FIGS. 1A and 1B. At step 441, while the valve is in aclosed state, the controller instructs the actuator mechanism to retractthe actuator plunger such that the diaphragm disengages the valve seat.The pressure transducer then senses the pressure applied against thetransducer by the diaphragm at step 443. The sensed pressure is relayedto the controller at step 445. At step 447, the controller compares thesensed pressure value to a pre-determined pressure value. The controllerthen instructs the actuator mechanism to further retract the actuatorplunger at step 449 such that the sensed pressure crosses apre-determined threshold value, signifying a valve open state has beenachieved. Optionally, in one embodiment, the controller instructs theactuator mechanism to further retract the actuator plunger at step 451until the sensed pressure reaches zero, signifying that the pressuretransducer has disengaged the diaphragm, the diaphragm is in a relaxedconfiguration, and the valve is completely open.

FIG. 5A is a flow chart illustrating the steps involved in achieving avalve close state of a fluid circuit using an actuator mechanism withfeedback control, comprising a force gauge, as described with referenceto FIGS. 2A and 2B. At step 522, the controller instructs the actuatormechanism to extend the actuator plunger such that the force gauge onthe contact end of the actuator mechanism engages the diaphragm.Optionally, at step 524, the force gauge senses force applied by thediaphragm against the force gauge. Then, at step 526, the controllerinstructs the actuator mechanism to close the valve by further extendingthe contact end of the actuator mechanism to push the diaphragm into theflow path of the fluid circuit. The force gauge then senses the forceapplied against the gauge by the diaphragm while the valve is in aclosed state at step 528. The sensed force is relayed to the controllerat step 530. At step 532, the controller compares the sensed force valueto a pre-determined force value. The controller then instructs theactuator mechanism to further extend or retract the actuator plunger atstep 534 such that the sensed force matches the pre-determined forcevalue, thereby ensuring complete valve closure. The force is continuallysensed at step 528 so that fine tune adjustments to the actuatorposition can be made in real-time to maintain the valve in a closestate.

FIG. 5B is a flow chart illustrating the steps involved in achieving avalve open state of a fluid circuit using an actuator mechanism withfeedback control, comprising a force gauge, as described with referenceto FIGS. 2A and 2B. At step 541, while the valve is in a closed state,the controller instructs the actuator mechanism to retract the actuatorplunger such that the diaphragm disengages the valve seat. The forcegauge then senses the force applied to the gauge by the diaphragm atstep 543. The sensed force is relayed to the controller at step 545. Atstep 547, the controller compares the sensed force value to apre-determined force value. The controller then instructs the actuatormechanism to further retract the actuator plunger at step 549 such thatthe sensed force crosses a pre-determined threshold value, signifying avalve open state has been achieved. Optionally, in one embodiment, thecontroller instructs the actuator mechanism to further retract theactuator plunger at step 551 until the sensed force reaches zero,signifying that the force gauge has disengaged the diaphragm, thediaphragm is in a relaxed configuration, and the valve is completelyopen.

FIG. 6 is a flow chart illustrating the steps involved in achieving avalve close state of a fluid circuit using an actuator mechanism withfeedback control, comprising a pressure transducer and a force gauge, asdescribed with reference to FIGS. 3A and 3B. At step 622, the controllerinstructs the actuator mechanism to extend the actuator plunger suchthat the pressure transducer and the force gauge on the contact end ofthe actuator mechanism engage the diaphragm. Optionally, at step 624,the pressure transducer senses the pressure applied by the diaphragmagainst the pressure transducer and the force gauge senses the forceapplied by the diaphragm against the force gauge. Then, at step 626, thecontroller instructs the actuator mechanism to close the valve byfurther extending the contact end of the actuator mechanism to push thediaphragm into the flow path of the fluid circuit. The pressuretransducer then senses the pressure applied against the transducer bythe diaphragm and the force gauge then senses the force applied againstthe gauge by the diaphragm while the valve is in a closed state at step628. The sensed pressure and sensed force are relayed to the controllerat step 630. At step 632, the controller compares the sensed pressurevalue to a pre-determined pressure value and the sensed force value to apre-determined force value. The controller then instructs the actuatormechanism to further extend or retract the actuator plunger at step 634such that the sensed pressure matches the pre-determined pressure valueand the sensed force matches the pre-determined force value, therebyensuring complete valve closure. The pressure and force are continuallysensed at step 628 so that fine tune adjustments to the actuatorposition can be made in real-time to maintain the valve in a closestate.

FIG. 6B is a flow chart illustrating the steps involved in achieving avalve open state of a fluid circuit using an actuator mechanism withfeedback control, comprising a pressure transducer and a force gauge, asdescribed with reference to FIGS. 3A and 3B. At step 641, while thevalve is in a closed state, the controller instructs the actuatormechanism to retract the actuator plunger such that the diaphragmdisengages the valve seat. The pressure transducer and force gauge thensense the pressure and force respectively, applied against thetransducer by the diaphragm at step 643. The sensed pressure and forceare relayed to the controller at step 645. At step 647, the controllercompares the sensed pressure value and sensed pressure value topre-determined pressure and force values. The controller then instructsthe actuator mechanism to further retract the actuator plunger at step649 such that the sensed pressure and force cross pre-determinedthreshold values, signifying a valve open state has been achieved.Optionally, in one embodiment, the controller instructs the actuatormechanism to further retract the actuator plunger at step 651 until thesensed pressure and sensed force both reach zero, signifying that thepressure transducer and force gauge have disengaged the diaphragm, thediaphragm is in a relaxed configuration, and the valve is completelyopen.

As discussed earlier, the actuator mechanism of the presentspecification can be used in a variety of applications having a membraneor diaphragm type valve in a fluid circuit. In various embodiments,depending upon the application, the actuator mechanism can be configuredto move the actuator to maintain the pressure or force within any rangeor at any value as sensed by the pressure transducer or force gaugerespectively, to keep the valve closed.

For example, in one embodiment, the actuator mechanism of the presentspecification can be used in a portable kidney dialysis system having adisposable manifold for fluidic circuits. One of ordinary skill in theart would appreciate that the actuator mechanism with feedback controlsystem could be implemented with a disposable manifold by positioningthe actuator external to the manifold at the desired valve location.This type of actuator is also separate and distinct from the disposablemanifold and generally part of the non-disposable portion of the kidneydialysis system. Valve systems are preferably implemented in adisposable type of manifold using elastic membranes at flow controlpoints which are selectively occluded, as required, by protrusions,pins, or other members extending from the machine. In variousembodiments, fluid occlusion is enabled using an on/off DC motor, astepper motor controlled by a controller, or a safe, low-energy magneticvalve. In one embodiment, the valve system is similar to that disclosedin U.S. patent application Ser. No. 13/023,490, assigned to theapplicant of the present invention, filed on Feb. 8, 2011, and entitled“Portable Dialysis Machine”, which is hereby incorporated by referencein its entirety. In another embodiment, the valve system is similar tothat disclosed in U.S. patent application Ser. No. 13/726,457, assignedto the applicant of the present invention, filed on Dec. 24, 2012, andentitled “Portable Dialysis Machine with Improved Reservoir HeatingSystem”, which is hereby incorporated by reference in its entirety. Inone embodiment, a valve actuator mechanism having a pressure transduceras disclosed in the present specification is used in a dialysis machineto maintain a sensed pressure of at least 2 psi, ensuring valve closure.In another embodiment, a valve actuator mechanism having a force gaugeas disclosed in the present specification is used in a dialysis machineto maintain a sensed force of at least 5 pound-force (lb_(F)), ensuringvalve closure. In yet another embodiment, a valve actuator mechanismhaving both a pressure transducer and a force gauge as disclosed in thepresent specification is used in a dialysis machine to maintain a sensedpressure of at least 2 psi and a sensed force of at least 5 pound-force(lb_(F)), ensuring valve closure.

In one embodiment, the diaphragms used as valves are similar to thosedescribed in the '490 application referenced above. In anotherembodiment, the diaphragms used as valves are similar to those disclosedin U.S. patent application Ser. No. 13/852,918, assigned to theapplicant of the present invention, filed on Mar. 28, 2013, and entitled“Manifold Diaphragms”, which is hereby incorporated by reference in itsentirety.

In general, the actuator mechanism with feedback control of the presentspecification can be used with a valve in a kidney dialysis systemhaving the following attributes: a) two stable states, open and closed,b) changing states requires energy input, c) maintaining a state doesnot require energy input, d) a state is changed by the use of electronicforces to modify the position of a displacement member which, whenmodified, causes a valve to either open or close.

The above examples are merely illustrative of the many applications ofthe system of the present invention. Although only a few embodiments ofthe present invention have been described herein, it should beunderstood that the present invention might be embodied in many otherspecific forms without departing from the spirit or scope of theinvention. Therefore, the present examples and embodiments are to beconsidered as illustrative and not restrictive, and the invention may bemodified within the scope of the appended claims.

We claim:
 1. A valve actuator system adapted to open and close a valve,comprising an orifice closing member, positioned within a manifold andadjacent a fluid pathway through which fluid flows in a dialysis system,said valve actuator mechanism comprising: a displacement member adaptedto being displaced linearly and having a contact end wherein saidcontact end is positioned proximate to said orifice closing member whensaid valve is in said open state; a motor for moving said displacementmember; at least one pressure sensor positioned on said contact end forsensing pressure generated when said contact end is in physicalcommunication with said orifice closing member and for relaying databased on said sensed pressure; and a controller for receiving the sensedpressure from the at least one pressure sensor, wherein said controllercomprises a memory having stored therein a plurality of programmaticinstructions that, when executed by a processing unit, compare saidsensed pressure to a pre-determined value stored in said memory andactivate said motor to move said displacement member toward or away fromsaid orifice closing member to optimally position the contact endagainst said orifice closing member.
 2. The valve actuator system ofclaim 1, wherein said motor comprises a stepper motor.
 3. The valveactuator system of claim 1, wherein said motor comprises a DC motor. 4.The valve actuator system of claim 1, further comprising an encoder fordetermining amount of movement of said displacement member.
 5. The valveactuator system of claim 1 for use in a dialysis machine.
 6. The valveactuator system of claim 5, wherein said controller is programmed tomaintain a sensed pressure of at least 2 psi.
 7. A valve actuator systemadapted to open and close a valve, comprising an orifice closing member,positioned within a manifold and adjacent a fluid pathway through whichfluid flows in a dialysis system, said valve actuator mechanismcomprising: a displacement member adapted to being displaced linearlyand having a contact end wherein said contact end is positionedproximate to said orifice closing member when said valve is in said openstate; a motor for moving said displacement member; at least one forcesensor positioned on said contact end for sensing force generated whensaid contact end is in physical communication with said orifice closingmember and for relaying data based on said sensed force; and acontroller for receiving the sensed force from the at least one forcesensor, wherein said controller comprises a memory having stored thereina plurality of programmatic instructions that, when executed by aprocessing unit, compare said sensed force to a pre-determined valuestored in said memory and activate said motor to move said displacementmember toward or away from said orifice closing member to optimallyposition the contact end against said orifice closing member.
 8. Thevalve actuator system of claim 7, wherein said motor comprises a steppermotor.
 9. The valve actuator system of claim 7, wherein said motorcomprises a DC motor.
 10. The valve actuator system of claim 7, furthercomprising an encoder for determining amount of movement of saiddisplacement member.
 11. The valve actuator system of claim 7 for use ina dialysis machine.
 12. The valve actuator system of claim 11, whereinsaid controller is programmed to maintain a force of at least 5pound-force (lb_(F)).
 13. A valve actuator system adapted to open andclose a valve, comprising an orifice closing member, positioned within amanifold and adjacent a fluid pathway through which fluid flows in adialysis system, said valve actuator mechanism comprising: adisplacement member adapted to being displaced linearly and having acontact end wherein said contact end is positioned proximate to saidorifice closing member when said valve is in said open state; a motorfor moving said displacement member; at least one pressure sensorpositioned on said contact end for sensing pressure generated when saidcontact end is in physical communication with said orifice closingmember and for relaying data based on said sensed pressure; at least oneforce gauge positioned on said contact end for sensing force generatedwhen said contact end is in physical communication with said orificeclosing member and for relaying data based on said sensed force; and acontroller for receiving the sensed pressure from the at least onepressure sensor and the sensed force from the at least one force gauge,wherein said controller comprises a memory having stored therein aplurality of programmatic instructions that, when executed by aprocessing unit, compare said sensed pressure to a pre-determinedpressure value stored in said memory and said sensed force to apre-determined force value stored is said memory and activate said motorto move said displacement member toward or away from said orificeclosing member to optimally position the contact end against saidorifice closing member.
 14. The valve actuator system of claim 13,wherein said motor comprises a stepper motor.
 15. The valve actuatorsystem of claim 13, wherein said motor comprises a DC motor.
 16. Thevalve actuator system of claim 13, further comprising an encoder fordetermining amount of movement of said displacement member.
 17. Thevalve actuator system of claim 13 for use in a dialysis machine.
 18. Thevalve actuator system of claim 17, wherein said controller is programmedto maintain a sensed pressure of at least 2 psi.
 19. The valve actuatorsystem of claim 17, wherein said controller is programmed to maintain aforce of at least 5 pound-force (lb_(F)).